Pinion construction

ABSTRACT

A pinion construction comprising a major toothed portion, a minor toothed portion and a shaft wherein there is a torsionally resilient driving means between the minor toothed portion and the shaft, and the teeth on the minor toothed portion are thicker than the teeth on the major toothed portion. A pinion of this construction may be used in a reversing gear drive to provide a reversing pinion which will not vibrate or rattle when it is idling during forward drive operation of the gear drive by virtue of tuning the natural frequency of the reverse gear branch to avoid torsional vibration resonancies.

United States Patent Richardson [151 3,682,015 1 Aug. 8, 1972 [54]PINION CONSTRUCTION [72} Inventor: William S. Richardson, Milwaukee,

Wis.

[73] Assignee: The Falk Corporation, Milwaukee,

Wis. [22] Filed: March 5, 1971 [2]] Appl. No.: 121,382

[58] Field of Search ..74/377, 810, 409-411,

[56] References Cited UNITED STATES PATENTS 1,197,261 9/1916 Burke..74/44O 1,404,816 1/1922 Wegstein ..74/440 2,943,504 1 7/1960 Falk etal. ..74/377 X Primary Examiner-Arthur T. McKeon Attorney-Donald G.Casser and Allen W. Leiser [57] ABSTRACT A pinion constructioncomprising a major toothed portion, a minor toothed portion and a shaftwherein there is a toisionally resilient driving means between the minortoothed portion and the shaft, and the teeth on the minor toothedportion are thicker than the teeth on the major toothed portion. Apinion of this construction may be used in a reversing gear drive toprovide a reversing pinion which will not vibrate or rattle when it isidling during forward drive operation of the gear drive by virtue oftuning the natural frequency of the reverse gear branch to avoidtorsional vibration resonancies.

7 Claims, 8 Drawing Figures PATENTEDAuc 8 m2 SHEET 1 OF 3 INVENTORWILLIAM s. RICHARDSON ATTORNEY PATENTEDMJG 8 I912 3.682.015 sum 2 or 3INVENTOR WILLIAM S. RICHARDSON ATTORNEY PATENTEDAus 8 I972 SHEET 3 BF 3BEARING I AT REST 3 FORWAR m M A 4/ m H mm N ES VM M W L Y B REVERSEATTORNEY PINION CONSTRUCTION BACKGROUND OF THE INVENTION This inventionrelates to a pinion construction which is adapted to eliminate or reducedamage to a pinion such as can be caused when it is in idle conditionwhile meshed with a driven gear being driven by another pinion.

Various types of gear drives incorporate one pinion which drives thedriven or bull gear in one direction and a second pinion which drivesthe bull gear in an opposite direction. Both pinions may be connected toclutches or other suitable elements so that one or the other can beselectively connected to the prime mover in order to drive the drivengear. When the gear drive is A main object of this invention is toprovide a pinion construction with a first portion rigidly attached toits shaft and a second portion attached to the shaft with torsionallyflexible drive means, wherein the first portion is adapted to transmitdriving loads and the second portion is adapted to prevent shock orvibration being a marine propulsion unit, for example, one pinion maynatural frequency of vibration of the reverse train, a

resonance occurs which produces high vibratory torque in the reversetrain. Problems can arise when the reverse pinion is in the idlecondition during forward operation of the gear drive in that vibrationsand sporadic rattles can be established in the reverse gear train whichcan often lead to breaking of gears and gear teeth or other physicaldamage to the reverse gear train system, as well as a noisy chatteringoperation of the reverse gear train when in its idle condition.

SUMMARY OF THE PRESENT INVENTION My present invention seeks to obviatethe problems caused by vibrations being established in a reverse pinionwhen in idle condition through the provision of a pinion constructionwhich includes a major toothed portion and a minor toothed portion bothsupported on a shaft element, wherein the minor toothed portion isconnected to the shaft through torsionally flexible driving means, andwherein the minor toothed portion has less backlash than the majortoothed portion of the pinion.

During forward operation of a gear drive incorporating a reverse pinionof this construction, the main gear being driven by another pinion woulddrive the reverse train through the minor toothed portion of the reversepinion and its torsionally flexible driving means to thereby tune thenatural response of the reverse train below any excitation frequencybecause of the flexibility in the system. During astem operation, thetooth loads would deflect the minor toothed portion of the pinionsufficiently to allow the major toothed portion to come into mesh withthe driven gear and transmit the driving load for reverse operation.Thus the minor toothed portion of my new pinion construction iscartransmitted to the drive train incorporating the pinion when it isinthe idle condition. Another main object is to provide a pinion withtwo separate toothed portions, one being so mounted as to be capable ofrelative motion in relation to the other. A more particular main objectis to provide a pinion with a major toothed portion and a minor toothedportion in which the minor toothed portion is retained on the pinionshaft and driven by torsionally flexible driving means. A specificobject of this invention is to provide the particular pinionconstructions hereinafter claimed.

DESCRIPTION OF THE DRAWINGS The present invention is further describedwith reference to the following drawings which illustrate severalspecific embodiments of the invention:

FIG. 1 is an end view of one form of gear drive with which the presentinvention may be employed;

FIG. 2 is a sectional view taken along the plane of line 2-2 of FIG. 1,with portions broken away, showing details of the gear drive andillustrating the pinion construction of the present invention;

FIG. 3 is an enlarged sectional view, partially broken away, showing thefirst illustrated embodiment of the present invention in greater detail;

FIG. 4 is a sectional view taken along the plane of line 4-4 of FIG. 3,with portions broken away, also showing details of the first embodimentof this invention;

FIG. 5 is a plan view illustrating a tooth of a pinion of the form shownin FIGS. 3 and 4 of this invention in mesh with a driven gear when thegear drive is at rest, and FIGS. 5A and 5B are similar views showing thegear drive in the forward and reverse drive conditions respectively; and

FIG. 6 is a longitudinal sectional view, with portions broken away,similar to FIG. 3 but illustrating a second embodiment of thisinvention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIGS. 1 and 2 illustrate areversing gear drive mechanism of known construction, see for example U.S. Pat. No. 2,304,031, to illustrate a typical gear drive with which thepresent invention may be incorporated. The gear drive is referred to bythe general reference numeral 1 and is contained within a housing 2 ofappropriate configuration. The gear drive includes a forward-drivepinion 3 which meshes with a driven gear 4.

The pinion 3 is carried on shaft 5 which is joumaled in walls ofthe'housing 2 and has an end 6 projecting therefrom, and the gear 4 iscarried on a shaft 7 journaled in the walls of the housing and has anend 8 projecting therefrom at the side opposite to the end 6 of shaft 5.

The end 6 of the shaft 5 of the forward-drive pinion carries a clutchelement comprising a clutch drum 9 attached near its outer end. Theclutch drum 9 is disposed within a coacting outer clutch element 10which carries a flexible annular tubular gland 11, which may be made ofrubber or a rubber composition reinforced in suitable manner. A secondouter clutch member 12 is joined to the first clutch member and carriesa second inflatable annular tubular gland 13 which is adapted to expandto cause driving engagement between clutch member 12 and a clutch drumelement 14 fixed to a flange 15 at the end of a hollow pinion 16. Theclutch glands 11 and 13 are each supplied with fluid under pressurethrough tubes such as tubes 22 and adapted to expand into drivingengagement with their respective clutch drums 9 and 14 or retract to adisengaged position. The hollow pinion 16 is supported in bearings 17and 18 mounted on the walls of the housing. The hollow pinion 16encircles the shaft 5 of the pinion 3 and is supported concentricallyand separately therefrom. The pinion 16 meshes with a pinion 19 carriedon a countershaft 20 journaled in the walls of the housing in suitablebearings and and running parallel to the shaft 5 of the forward-drivepinion. The countershaft 20 at its opposite end includes a pinion 21that meshes with the driven gear 4 to act as the reverse-drive pinion.

In a typical installation on a ship, the engine, which may comprise aninternal combustion engine or steam or gas turbine, may be connected tothe shaft 23 through a suitable coupling, and the propeller shaftconnected to the end'8 of the shaft 7 which projects from the oppositeside of the housing of the gear drive. The coaction of the variouselements is such that when both clutch glands 11 and 13 are deflated,pinions 3 and 21 and driven gear 4 are stationary or at rest. When theclutch gland 11 is inflated and the clutch gland l3 deflated, (thecondition shown in FIG. 2), the pinion 3 rotates to drive the drivengear 4 in the forward direction, while the pinion 21 is in an idlecondition. On the other hand, when the clutch gland 11 is deflated andthe clutch gland 13 inflated, the pinion 16 meshes with the pinion 19 toallow the pinion 21 to drive the driven gear 4 in the reverse direction,while the forward pinion 3 is in an idle condition.

The pinion 21 as shown in FIGS. 2-5 is constructed in accordance withthis invention and includes a major toothed portion and a minor toothedportion 31, both supported on the shaft 20. The pinion is shown in FIG.2 as a herringbone or double-helical type, although it may be made withother tooth forms such as spur, single-helical, etc.

A section of the pinion 21 is shown in detail in FIG. 3. The majortoothed portion 30 is illustrated as being formed integral with theshaft 20, but it may also be a separate element rigidly affixed to theshaft. A bushing 32 having a hub 33 and an annular collar 34 is insertedbetween the minor toothed portion 31 and the shaft 20 and is fastened tothe shaft by means of set screws 35 spaced about the circumference ofthe bushing. The inner surface 36 (see FIG. 4) of the minor toothedportion 31 rides on the outer surface of the hub 33 of the bushing. Theminor toothed portion 31 is connected to the bushing 32 by a pluralityof torsionally flexible cylindrical keys 37 which are made of rubber,neoprene, or other resilient material. The torsionally flexible keys 37are carried in apertures 38 of which the upper section 38a is formedalong the inner portion of the minor toothed portion 31 and thelowersection 381) posite side bears against a frictional spacer ring 40 whichis urged thereagainst by a series of springs 41 carried in recesses 42formed in the major toothed portion 30; in this fashion, the minortoothed portion 31 is located axially on the shaft 20 of the pinion. Thefrictional spacer ring 40 (which may be made of bronze, brake material,and the like) is an optional element which is intended to augment thetorsional frictional resistance and damping to the minor toothed portion31 where needed to supplement the torsional resistance provided by theflexible keys 37 (or the springs 47 described below with respect to FIG.6).

Turning now to FIG. 5, which illustrates a horizontal sectional viewshowing the pinion 21 meshed with the gear 4, the thickness of teeth tothe major toothed portion 30, shown as W in FIG. 5 is less than thethickness W of the teeth of the minor toothed portion 31. Thus there isgreater backlash between the teeth of the major toothed portion 30 and atooth space 4a of the gear 4 than there is between the teeth of theminor toothed portion 31 and the tooth space 4a. The purpose of thisdifference in teeth thickness is discussed in the next paragraph.

The operation of the pinion 21 will now be explained with reference toFIGS. 5-5b. In FIG. 5, the at rest condition is illustrated, and thereis clearance on either side of the teeth of the major toothed portion 30and the minor toothed portion 31 of the pinion 21 and the surroundingteeth 4b of the driven or bull gear 4. This condition obtains when boththe reverse pinion 21 of this invention and forward drive pinion 3 (seeFIG. 2) are de-clutched. When the clutches are actuated so that thedrive is in the forward drive condition indicated by the arrow 43 inFIG. 5a, (i.e. clutch gland l 1 is inflated, and clutch gland 13 isdeflated, see FIG. 2) the gear 4 will be driven by the forward pinion 3,and the reverse pinion 21 will be in its idle condition, i.e. it isde-clutched. As shown in FIG. 5a, the action of the pinion 21 is suchthat the teeth of the minor toothed portion 31 will contact a side 4c ofthe tooth of the gear 4, and because the thickness W of the teeth ofthis portion 31 is greater than the thickness W, of the teeth of themajor toothed portion 30, the teeth of the latter will not contact thesides of the teeth 4b on the gear 4. Further, the material of thetorsionally resilient driving keys 37 is chosen to have suitablestiffness that will prevent the teeth of the major toothed portion 30from contacting the teeth on the bull gear 4. In this condition, inwhich the reverse pinion 21 is in an idle state, the bull gear 4 willdrive the reverse gear train through the minor toothed portion of 31which, because of the torsionally resilient means 37, is a flexibledriving engagement and thereby the natural response of the reverse trainis tuned below any excitation frequency which would cause vibrations orrattling that might lead to tooth or gear damage or excessive wear. Whenthe gear 4 is to be driven in the reverse direction as indicated by thearrow 44 in FIG. 5b, i.e. the clutch gland 11 is deflated and the clutch13 is inflated, power from the prime mover is transmitted through to thereverse pinion 21 and, in such condition, the teeth of the minor toothedportion 31 will contact a side 40 of the teeth 4b of the bull gear butthe power from the prime mover will be sufficient to cause the teeth onthe major toothed portion 30 to also contact the sides 4c of the bullgear teeth because, under driving load, the torsionally resilientdriving means 37 will enable this relative twisting or relative motionbetween the two portions of the pinion 21. Thus in the reverse drivecondition, the teeth on the major toothed portion will transmit thedriving load from the prime mover to the bull gear 4. The face width ofthe teeth on the major toothed portion should be sufficient to transmitthe loads which will be encountered during the reverse drive state.

FIG. 6 illustrates a second embodiment of my new pinion constructionwherein the torsionally resilient driving means connecting the minortoothed portion 31 of the pinion to the shaft 20 comprises a pluralityof springs 47. As with the torsionally resilient rubber keys 37illustrated in FIG. 3, the torsionally resilient springs 47 are chosenso as to have sufficient stiffness to prevent the major toothed portion30 from coming into contact with the driven gear when the pinion 21 isin its idle condition, but enabling deflection between the major toothedportion 30 and minor toothed portion 31 when a driving load istransmitted to the pinion 21.

It has been calculated, for example, that if the minor toothed portion31 of the pinion 21 had to take up about 5 horsepower when the pinion isin an idle condition while meshed with a driven gear, the force on thetorsionally resilient driving means 37 or 47 would be on the order ofabout 100 1b., and the stiffness of such driving means could be on theorder of 0.05 X inch pounds per radian to give the desired action. Thenatural response frequency of the reverse train with the amount offlexibility would be only about 1.5 cps.

There has thus been described a new pinion construction comprising twotoothed portions mounted on a shaft: a major toothed portion which isrigidly mounted on the shaft and a minor toothed portion which iscarried on the shaft, and adapted for relative movement in relation tothe major toothed portion, by means of torsionally flexible drivingmeans. The terms major and minor are defined herein tomean that themajor toothed portion is to comprise over 50 percent of the face widthof the particular pinion construction and the minor toothed portion isto comprise less than 50 percent thereof. The particular face width ofthe major tooth portion will, in accordance with usual gear design, beselected to be sufficient to transmit the driving loads which will beencountered in the specific gear drive with which the pinion of thisconstruction would be used. The minor toothed portion operates to drivethe reverse gear train when the pinion is in an idle condition andreduce or eliminate vibrations which can be transmitted to such trainwhen it is in idle, thereby lessening the potential for damage to thereverse pinion itself or its associated gears or other equipment. Thepinion construction disclosed herein may be used in various types ofgear drive in additionto the marine unit shown in the drawings, such asdrives for loaders, cranes, bulldozers, industrial tractors, and otherdrives which include reverse gearing that idles freely during forwardoperation of the drive.

Although two specific embodiments of this invention have been hereindescribed for the purposes of illustration, it is expected that changescan be made in the described embodiments and that other embodiments canbe devised which will still be within the concept of this invention, andit is understood that it is intended to cover all such changes andmodifications which do not constitute a departure from the true spiritand scope of this invention.

lclaim:

1. A pinion construction comprising, in combination:

a shaft;

a major toothed portion rigidly mounted on the shaft;

a minor toothed portion, and torsionally resilient drive meansconnecting the minor toothed portion to the shaft;

the teeth of the minor toothed portion being thicker than the teeth ofthe major toothed portion.

2. A pinion according to claim 1, wherein:

the torsionally resilient driving means includes a bushing elementattached to the shaft and a plurality of resilient driving keysconnecting the minor toothed portion to the bushing element.

3. A pinion construction according to claim 2 wherein the bushingelement includes a hub portion on which the minor toothed portion of thepinion is supported and a collar portion which bears against a side ofthe minor toothed portion.

4. A pinion according to claim 1, further including:

spacer means positioned between the major toothed portion and the minortoothed portion; and

spring means carried by the major toothed portion and arranged to urgethe spacer means against the minor toothed portion.

5. A pinion construction comprising, in combination:

a shaft;

a major toothed portion rigidly mounted on the shaft;

a bushing element mounted on the shaft and including a hub portioncarried on the shaft and a collar portion; a minor toothed portion whichis rotatably mounted on the hub portion ofthe bushing element;

torsionally resilient drive means connecting the minor toothed portionto the hub portion of the bushing element; and

spacer means between the major toothed portion and the minor toothedportion and arranged to bear against one side of the minor toothedportion, the collar portion of the bushing element being an ranged tobear against an opposite side of the minor toothed portion.

6. in a gear drive having a driven gear, a forward pinion meshed withthe driven gear to drive it in one direction, a reverse pinion meshedwith the driven gear to drive it in an opposite direction, and means toselectively connect one of said pinions to a prime mover to drive thedriven gear while the other pinion rotates in an idle condition, theimprovement wherein:

the reverse pinion comprises a shaft, a major toothed portion rigidlymounted on the shaft, a' minor toothed portion mounted on the shaft androtating relative to the major toothed portion, the teeth of the minortoothed portion being thicker than the teeth of the major toothedportion, and the teeth of both portions being meshed with teeth of thedriven gear;

.7 8 the minor toothed portion contacting the sides of the shaft, saiddriving means being flexible to teeth of the driven gear when thereverse pinion is admit relative motion between the minor toothed in anidle condition with-the teeth of the major ti d th ajor toothed portionwhen the Pg :Omon bemg out of amulet" with Said reverse pinion transmitsdriving loads but limit s1 es; an

relative motion between the minor toothed portion and major toothedportion when the reverse pinion is in an idle condition to therebyprevent contact between teeth of the major toothed portion and teeth ofthe driven gear when the reverse pinion is in an idle condition.

both the major toothed portion and the minor toothed portion contactingthe sides of teeth of the driven gear when the reverse pinion isconnected to a prime mover to drive the driven gear.

7. A gear drive according to claim 6, wherein 10 the reverse pinionincludes torsionally resilient driving means connecting the minortoothed portion to

1. A pinion construction comprising, in combination: a shaft; a majortoothed portion rigidly mounted on the shaft; a minor toothed portion,and torsionally resilient drive means connecting the minor toothedportion to the shaft; the teeth of the minor toothed portion beingthicker than the teeth of the major toothed portion.
 2. A pinionaccording to claim 1, wherein: the torsionally resilient driving meansincludes a bushing element attached to the shaft and a plurality ofresilient driving keys connecting the minor toothed portion to thebushing element.
 3. A pinion construction according to claim 2 whereinthe bushing element includes a hub portion on which the minor toothedportion of the pinion is supported and a collar portion which bearsagainst a side of the minor toothed portion.
 4. A pinion according toclaim 1, further including: spacer means positioned between the majortoothed portion and the minor toothed portion; and spring means carriedby the major toothed portion and arranged to urge the spacer meansagainst the minor toothed portion.
 5. A pinion construction comprising,in combination: a shaft; a major toothed portion rigidly mounted on theshaft; a bushing element mounted on the shaft and including a hubportion carried on the shaft and a collar portion; a minor toothedportion Which is rotatably mounted on the hub portion of the bushingelement; torsionally resilient drive means connecting the minor toothedportion to the hub portion of the bushing element; and spacer meansbetween the major toothed portion and the minor toothed portion andarranged to bear against one side of the minor toothed portion, thecollar portion of the bushing element being arranged to bear against anopposite side of the minor toothed portion.
 6. In a gear drive having adriven gear, a forward pinion meshed with the driven gear to drive it inone direction, a reverse pinion meshed with the driven gear to drive itin an opposite direction, and means to selectively connect one of saidpinions to a prime mover to drive the driven gear while the other pinionrotates in an idle condition, the improvement wherein: the reversepinion comprises a shaft, a major toothed portion rigidly mounted on theshaft, a minor toothed portion mounted on the shaft and rotatingrelative to the major toothed portion, the teeth of the minor toothedportion being thicker than the teeth of the major toothed portion, andthe teeth of both portions being meshed with teeth of the driven gear;the minor toothed portion contacting the sides of teeth of the drivengear when the reverse pinion is in an idle condition with the teeth ofthe major toothed portion being out of contact with said sides; and boththe major toothed portion and the minor toothed portion contacting thesides of teeth of the driven gear when the reverse pinion is connectedto a prime mover to drive the driven gear.
 7. A gear drive according toclaim 6, wherein the reverse pinion includes torsionally resilientdriving means connecting the minor toothed portion to the shaft, saiddriving means being flexible to admit relative motion between the minortoothed portion and the major toothed portion when the reverse piniontransmits driving loads but limit relative motion between the minortoothed portion and major toothed portion when the reverse pinion is inan idle condition to thereby prevent contact between teeth of the majortoothed portion and teeth of the driven gear when the reverse pinion isin an idle condition.